Escherichia coli

Background

Microbiology

• Lactose-fermenting Gram-negative bacillus within the Enterobacteriaceae
• Can also be non-lactose-fermenter on MacConkey agar that is β-hemolytic on SBA
• Member of commensal gut flora

Classification

• Has multiple pathotypes
  • Extraintestinal pathogenic E. coli (ExPEC): causes UTI and neonatal meningitis
    • Strains that cause neonatal meningitis are more likely to produce K1 capsule and S fimbriae
  • Enteropathogenic E. coli (EPEC): produces localize adherence pilus, causes severe acute watery diarrhea that can become chronic
  • Enterotoxigenic E. coli (ETEC): produces enterotoxins, causes acute watery diarrhea
  • Enterhemorrhagic E.coli (EHEC) and Shiga toxin-producing E. coli (STEC): produces Shiga (or related) toxins, causes watery and bloody diarrhea and can lead to HUS
  • Enteroaggregative E. coli (EAEC): produces adherence factors, causes mucoid diarrhea that can become chronic
  • Enteroinvasive E. coli (EIEC): spreads cell-to-cell, causes watery diarrhea or dysentery
  • Diffuse-adhering E. coli (DAEC): causes diarrhea